[Diy_efi] Magesquirt vs D- jetronic

[John Nevius]

Almost on MegaSquirt. . .

It can operate as a true mass flow system (it knows the amount of O2 being sucked into the engine by knowing the temperature of the intake charge and its absolute pressure) or in a alpha-N mode (based on the engine speed and angle of the throttle plate).  Mass flow is normally better, however engines with a high cam overlap sometimes produce erratic vacuum readings.  There are variants available that allow you to run alpha-N at low RPMs and mass flow at higher RPMs.  

Throttle position can be used with mass flow to simulate an accelerator pump on a carb'd car (momentarily increase the squirt when the throttle is opened).

MegaSquirt is quite adaptable to most any sensor type found in your car, the default is for GM sensors (cheap and easily available in the US).  You need to supply temperature sensors for coolant temperature (used to control warm up) and intake air temperature (for the mass flow calculation).  The barometric pressure sensor is included in the kit.

Cheers!

John N

Tomas J. Sokorai Sch. wrote:

> On Thursday 21 April 2005 08:47, spati wrote:
> >
> > Is the Megesquirt based on the same things ??
> >
> 
> Yes, and no.
> It's load sensing is based on intake vacuum, so it is like D-jetronic, but it 
> is light years more advanced.
> D-jetronic was a very crude analog injection system. No microcontroller that 
> calculated the fueling strategy, just a couple of transistors and discrete 
> components (very few transistors, BTW, as at the time D-jetronic was 
> designed, transistors were not particularily cheap)
> Megasquirt is digital, and calculates mathematically the amount of fuel 
> injected based on RPM, intake vacuum, throttle butterflies position, RPM, 
> engine temperature, intake air temperature and even corrects the calculation 
> taking into account the barometric pressure.
> And that's only the open loop strategy, as Megasquirt has also the capability 
> to trim the amount of fuel based on the actual combustion results of the 
> engine, using feedback from an exhaust oxygen sensor (normal or wideband).
> 
> -- 
> Tomas J. Sokorai Sch.
> _______________________________________________
> Diy_efi mailing list
> Diy_efi at diy-efi.org
> http://lists.diy-efi.org/mailman/listinfo/diy_efi